This application is based on Japanese Patent Application No. 172722/1998 filed on Jun. 19, 1998, the contents of which are incorporated herein by reference.
1. Field of the Invention
This invention relates to an apparatus for displaying an image, and in particular the invention concerns itself with the art of virtual reality or computer visualization which includes projecting an image on a screen, the shape of which is optional, and presenting the object on the screen so as to afford an interactive environment to the observer.
2. Description of the Prior Art
In recent years, notable progress has been made in the field of a system for producing virtual reality. Various types of head-mounted displays (HMDs) have been proposed and manufactured as one of the new apparatuses for presenting visual information in a virtual space. Each of the HMDs includes a display apparatus arranged around the observer's head.
Another new apparatus of the kind indicated above is of a projection type and is constructed so as to allow an image to appear on a flat rectangular screen by means of a projector. A system of this type is disclosed in U.S. Pat. No. 3,200,702. This type of apparatus designed to enable a plurality of observers to view an image simultaneously makes it possible to view a proper image from more places.
It has been the purpose of either of the aforesaid prior art apparatuses to present a virtual "space" per se. It is contemplated, however, that they will be found even more advantageous when used in doing some work in the virtual space. For this purpose, the presentation of a virtual "object" appears even more important than the presentation of the virtual "space" per se.
In order to make the virtual object true to nature, it is necessary for the observer to exert an influence on the image in an interactive manner. Input means heretofore used for this purpose have taken the form of input devices separated from screens. These input devices have the disadvantage that, because of a discord between the position of the image presented and the position in which manual input procedures are carried out, the aforesaid input devices fail to let the observer feel as if he or she were manipulating the virtual object presented on the screen.
An attempt has been made to obtain the measurement values representing the position of a hand or hands of a person putting on an HMD and manipulating a visually presented object. The aim of this measurement is to allow the position of the hand or hands to agree with the position of the object. Even in this case, the observer cannot obtain the sense of holding the object with a tactile sensation.
According to still another prior proposal made to cope with the aforesaid problem, measurement values representing the position and attitude of an object presented on a display screen are obtained with a view to manipulating the object. A small-sized cathode ray tube or liquid crystal display is used as an apparatus of the kind indicated above. It is found that the flat display screen makes it difficult to attain a happy blending of visual and tactile sensation, which are of importance to the space recognition of human beings.